Topic 8: Cell Physiology II

Question 1

Cell Physiology Overview

Answer 1

Cells = living building blocks of body

• chemical processes in body (performed by cells) = metabolism
  
  • anabolism = building molecules
  • catabolism = breakdown of molecules

Question 2

Basic Cell Processes

Answer 2

• Protein Synthesis
• ATP Catabolism
• Cellular Respiration

Question 3

Protein Synthesis

Answer 3

-proteins can be enzymes, structural, etc. 
process of protein synthesis involves:
-DNA Transcription 
-mRNA Translation 
-After Translation

Question 4

DNA Transcription

Answer 4

-DNA ⇒ mRNA (messenger RNA)
steps:
-DNA uncoils at site of gene to expose gene base sequence
-RNA strand is formed, using code on DNA template to add complementary RNA nucleotides
e.g. DNA Template. . . . . . A T C G C A
mRNA. . . . . . . . . . . . . U A G C G U*
* in RNA – uracil (not thymine)

Question 5

mRNA Translation

Answer 5

-mRNA ⇒ proteins
steps:
-mRNA associates with ribosomes
-3 bases on mRNA = base triplet = a codon (e.g. CUU, ACG, etc)
-each codon codes for 1 amino acid (aa’s can have more than one codon)
-transfer RNA (tRNA) with attached specific aa and anticodon (complimentary bases to codon) binds to matching RNA
-peptide bond is formed to attach aa to growing peptide chain

Question 6

After Translation

Answer 6

• proteins produced on free ribosomes - released into cytosol or go to nucleus or mitochondria
• proteins produced by ribosomes on ER (RER) - released into ER lumen
  
  • modified by addition of sugars (glycoprotein)
  • transferred to Golgi complex in vesicles

Question 7

Golgi complex

Answer 7

further modifies protein by:
-carb changes/additions (act as an address to send them to the right destination)
-lipid additions
packages modified proteins (in vesicles) and sends to destination: cell membrane, secretion, lysosomes

Question 8

Lysosomes

Answer 8

membrane-bound organelles containing digestive enzymes (acid environment)

Question 9

Enzymes: (names end in ase)

Answer 9

• increase reaction rates
• not used up in reaction
• very sensitive to pH, temperature
• very specific

Question 10

ATP Catabolism

Answer 10

Adenosine Triphosphate (ATP):

• adenine + ribose (= adenosine) + 3 phosphates
• energy stored in phosphate bonds (covalent)
• energy produced used for reactions (protein synthesis, active membrane transport, muscle contraction, etc.)
• little ATP is stored, so constantly have to make it

Question 11

Cellular Respiration

Answer 11

production of ATP using glucose
-glucose enters most cells by facilitated transport (may be ⇑ in some cells by insulin)
overall:
1 glucose (C6H12O6) + 6 O2 ⇒ 6 CO2 + 6 H2O + 32 (max) ATP + heat

Question 12

Cellular Respiration steps

Answer 12

• glycolysis (anaerobic) in cytosol (2 ATP)
• enters mitochondria – becomes aerobic
• Krebs Cycle (2 ATP)
• Electron Transport Chain (28 ATP)
• 32 total ATP

Question 13

Cellular Respiration in the body

Answer 13

glycogen ⇒ glucose ⇒ ATP
proteins:
-some aa can be converted to pyruvic acid or enter Krebs cycle - depending on body’s need may form new glucose (liver, kidney) or ATP (most cells)
fats
-primary storage form of energy in the body (triglycerides)
-broken down to form acetyl CoA ⇒ ATP